Reporting on emerging science can sometimes feel like watching a live ultramarathon. Sure, there are occasional dramatic moves, but for the long haul it feels like nothing is happening. Fatigue builds up, blisters start to form, you miss the aid station… Evidence builds up slowly, and it’s only later that you know when the results are resolved.
In that spirit, I have some mid-race updates on the potential detrimental effects of excessive endurance exercise, a long-standing concern. We summarized the current state of the evidence last summer. Of course, it would be nice to have conclusive evidence on whether marathon or ultramarathon training can damage the heart. It became clear. Because you can’t randomize people to spend decades running marathons or lying on the couch. New research fills some important gaps.
hard arteries
The first one is British Journal of Sports Medicine, explores the link between exercise and atherosclerosis, the buildup of plaque that narrows and hardens arteries. One way to test for atherosclerosis is to obtain a coronary artery calcium (CAC) score. That’s it. It uses a CT scan to assess the amount of calcium present in the arteries of the heart. Recent evidence suggests that master endurance athletes tend to have higher her CAC scores than non-athletes. This is probably due to the wear and tear from pumping all the blood over the years during exercise. This is not good because a high CAC score reliably predicts an increased risk of serious and potentially fatal heart disease in the general population.
Fortunately, endurance athletes tend to have different plaques than their non-endurance counterparts. Athletes have plaques that are smooth, hard and resistant to rupture. Non-athletes have soft plaque that is more likely to detach from arterial walls and block blood flow. But no one has proven how this works in the real world.
This is where new research comes into play. His Pin-Ming Liu-led group at Sun Yat-sen University in China analyzed data from longitudinal studies in which subjects underwent his baseline CAC test in 2000 or 2001. After 5 or 10 years he underwent the CAC test, and during the study he completed a questionnaire on exercise habits at least three times. These repeated measures are very important because they can distinguish between people with high CAC scores (perhaps simply due to genetic bad luck) and those with elevated scores (perhaps due to lifestyle factors such as exercise).
They studied three groups totaling about 2,500 subjects. Those who consistently met or slightly exceeded recommendations. People who have at least three times the recommended average. In this case, the recommended amount of exercise is 150 minutes of moderate-intensity activity or 75 minutes of vigorous activity per week based on public health advice, with activities such as running counted as vigorous.
There were two important conclusions. First, in agreement with previous studies, the group doing the most exercise was actually more likely to have increased CAC scores on the second test. Regardless, the high-exercise group was less likely to suffer adverse cardiac events during study follow-up. does not carry the same risks as plaque in sedentary people.
This is far from the final word on this topic. One reason for this is that only some subjects had exercise levels comparable to those of elite endurance athletes. However, it is an encouraging sign that CAC scores have different meanings for non-exercise and exercise individuals.
J-curve
Discussions about CAC scores and other risk factors can feel a bit abstract. The research many of us aspire to is simpler. Take a bunch of people, find out how much they exercised, and wait to see who dies first. While there are many such studies, he said that there are many differences beyond exercise habits between those who choose to run 100 miles a week and those who choose not to run at all. , the results are difficult to interpret.
Despite these caveats, there were two studies. One from the Cooper Clinic in Texas and one from Copenhagen claim to show an “inverted J-curve” in the relationship between physical activity and mortality risk. A little exercise dramatically reduced the chance of premature death. Doing more resulted in even smaller increases. But overdoing it caused the curve to curve upwards and the risk started to increase again.
Many other studies have tested the same idea, but found no evidence that moderate exercise increases the risk of premature death. But given the imprecision inherent in this kind of observational data, it’s hard to tell which studies to trust (especially if you really want a specific conclusion), so I usually don’t recommend overexercising. We will not report another study that found it to be ineffective. bad for you after all.
There is an interesting twist to this though.is published in circulation, by a group led by Dong Hung Lee of the Harvard TH Chan School of Public Health, following 116,221 adults from the Nurses’ Health Survey and Health Professionals Follow-up beginning in the 1980s. In 30 years he killed over 47,000 subjects. In other words, we are not drawing conclusions based on a small number. (The aforementioned Copenhagen study famously suggested that “intense” running increased the risk of premature death.
An important detail is that subjects in the new study were asked about their exercise habits every two years, rather than just once at the beginning of the study. Rather than relying on guesses at 30-year health status, we were able to divide subjects into groups based on their average exercise level during the study period.
The main result was that people who did 150 to 300 minutes of vigorous exercise such as running (or 300 to 600 minutes of moderate exercise such as walking) per week were about half as likely to die during the study. It means that The risk was about one-fourth even after adjusting for other secondary benefits of exercise, such as lower body mass index. Note that 300 minutes a week equals 5 hours of running. It’s not a grueling ultramarathon training program, but it’s still a fair amount of exercise.
For those working five or more hours a week, the benefits were about the same. At least they did when average physical activity levels were used over the course of the study. When the analysis was rerun using only the exercise questionnaire, the inverse J-curve reappeared. Researchers point out that there are several problems with relying on a single measure of exercise habits. That includes the risk of reverse causation. Poor health status prior to baseline assessment may prompt more exercise, leading to the false impression that exercise is detrimental to health. This is how almost all previous studies on exercise and mortality have been conducted, and the new results suggest that J.
It’s still too early to say for sure that years of serious endurance training aren’t affecting the heart. It is not surprising that these changes have sometimes had a negative impact. However, epidemiological evidence continues to accumulate evidence that the overall effect on longevity is positive or, at worst, neutral. Is not.
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